Pressure reducing valve



Sept. 19, 1950 S. E. WESTMAN PRESSURE REDUCING VALVE Filed Jan. 2l, 1946 INVEN TOR. SYDNEY E. WESTMAN gm e,

AT TOR/VEY Patented Sept. 19, 1950 UNITED STATES PATENT OFFICE PRESSURE REDUCIN G VALVE Sydney E. Westman, Los Angeles, Calif., assigner to Bendix `Aviation Corporation, South Bend, Ind., a corporation of Delaware Application January 21, 1946, Serial No. 642,576

3 Claims. l

This invention relates to pressure reducing valves adapted to be connected between a high pressure line and a low pressure line, and to maintain a predetermined pressure in the low pressure line by controlling the flow thereto from the high pressureline. The valves oi the present invention are particularly adapted for use in hydraulic power systems, although they are not restricted to such use.

An object of the invention is to provide a reliable and quiet pressure reducing valve.

Another object is to provide a pressure reducing valve that also functions as a relief valve to relieve excessive pressures that may be developed in the low pressure line from various causes.

Another object is to provide a pressure reducing valve of pilot-type, that is capable of handling large flows without requiring the ,use of extremely large balancing springs.

Another object is to provide a pressure reducing valve construction such that the Valve can be changed from a pilot-type valve to a nonpilot type valve, or vice versa, by the interchange of a relatively few parts.

Another object is to provi-de a pilot type pressure reducing valve `of particularly simple construction.

Other advantages and features of the invention will become apparent from the detailed description to follow, with reference to the drawing; in which:

Fig. l is a longitudinal sectional view through a non-pilot type pressure reducing valve in accordance with `the invention.

Fig. 2 is a longitudinal sectional View of a portion of Fig, 1 showing the valve adapted for pilot operation; and

Fig. 3 is a longitudinal section showing an alternative construction of pilot type pressure reducing valve in accordance with the invention.

Referring t Fig. l, the valve therein disclosed has a casing consisting of a body I0, a spring housingr ll, and an end closure cap I2 for the housing il. The three parts may be joined together by long screws I3, which extend through the closure cap I2, and are threaded into thebOdy l0.

`The body Ill has a highpressure port III, a low pressure port I5, and a relief port I6. The high pressure` port I4 may be connected to a source of fluid at high pressure, and the port I5 may be connected to a system which is to be supplied with fluid at a constant pressure lower than the pressure of the huid supplied to port Ill. The relief port It may be vented to the atmosphere spring housing H.

or to a reservoir from which fluid is supplied by a pump to the high pressure port III.

The high pressure port I4 is connected to the open end of a cup-shaped member I'I, having a valve seat i8 in its bottom end, through which fluid is supplied to the low pressure port I 5, under the control of a poppet valve I 9. The cup-shaped member Il is sealed at its upper end with respect to a bore 2t in the body Ill, by a sealing ring 2i, The lower exterior surface of the cupshaped member il is threaded and screwed into the upper end of a sleeve 22, which is litted in the bore 2l) of the body I0, and is sealed with respect thereto by a pair of annular seals 23 and 24.

The bore 22 of the body I@ is enlarged intermediate the seals 2l and 23 to denne an annular chamber 25, which is connected to the low pressure port I5, and the bore 20 is enlarged intermediate the seals 23 and 24 to denne an annular chamber 25 connected to the relief port I6. The cup-shaped member Il and the sleeve 22, conected to it, are retained in position in the bore 2t by inwardly extending shoulders 21 on the The sleeve 22 defines a bore containing a piston 28, which is sealed with respect to the bore by spaced sealing rings 29 and 30. The piston 2B is recessed intermediate the sealing rings 29 and t@ to denne with the bore 22! of the sleeve, an annular chamber 3l, which is connected by radial passages 32 in the sleeve,

to the chamber 26. The piston 28 has an axial passage 33 extending therethrough from the upper end, and connected to the Chamber 3I by radial passages 34. rEhe upper end of the piston 28 `defines with the bore 22| and the lower end of the member Il, a chamber 35, which is connected by radial passages 36 in the sleeve 22 to the cham-ber 25.

rPhe poppet I9 has a stern I9l, on the lower end of which there is an auxiliary poppet 3l, which is adapted to close the upper end of the piston passage 33.

The piston 28 is constantly urged upwardly by a helical compression spring 39, which is compressed between the lower end of the piston 28 and a `spring loading member Ilil, which is slidable but not rotatable in the spring housing II, and is threaded on to a screw 4I, which extends `through the end cap I2 and has a handle 42 on its outer end. A thrust bearing Il3 is provided in the end cap I2 to take the thrust of the screw. The handle 42 may be provided with a springpressed ball detent M, adapted to engage in one more recesses l5 in the outer surface of the will be noted that in order for the piston 28a to be moved upwardly by its spring, it is necessary only that the spring overcome the force of the low pressure uid in the chamber 41 acting on the annular piston face 28| a and the auxiliary poppet 31a, and the force of the high pressure iiuid in port 14a acting against the pilot poppet 56. The pilot poppet can be made sufficiently small so that the force developed thereagainst by the high pressure fluid is not serious.

When the pressure in the low pressure port |a rises, the piston 28a is moved downwardly, causing the pilot poppet 56 to approach its seat, thereby throttling uid flow to, and reducing the pressure in, the chamber 51, permitting the piston 5| and the main poppet 52 to move down wardly until the main poppet seats.

If the pressure in the low pressure port |5a continues to rise further, the piston 28a will be moved downwardly to open the auxiliary poppet 31a, and permit the escape of fluid from the low pressure port through the passages 5|), chamber 41, passages 33a and 34a, the chamber 3|a and the passages 32a to chamber 26a and the relief port Ha, until the excess pressure is dissipated, whereupon the piston 28a will again rise to close against the auxiliary poppet 31a.

It will be observed fluid escaping from the chamber 51 between the stem 56| and the passage 48| flows through the chamber 41 and the passage 58 to the chamber 25a connected to the low pressure port |5a. If desired, this fluid can escape past the poppet piston 5| into the `chamber 58 and thence through the passages 59 to the chamber d. of the sealing ring 54 and the frictional resiste ance to movement of the piston that is caused by the sealing ring. Where the fluid is permitted to escape past the piston 5|, it may in some instances be desirable to provide a sealing ring between the stem 55| and the passage 48|.

The relative dimensions of the parts in Fig. 2 must be properly chosen relative to the pressures that are to be handled. Obviously, in order for the piston 5| to open the main poppet 52, the

piston must have an area such that the force developed against the underside of the piston by high pressure fluid in the chamber 51 will be greater than the force exerted against the upper side of the piston by the low pressure fluid in the chamber 5S plus the differential force exerted against the main poppet 52 by the high pressure nuid in the port |4a and the low pressure in chamber 58. When the values of the high pressure in the port 4a and the desired low pressure in the port |5a are known, the dimensions of the main poppet 52 and the piston 5| can be readily calculated.

There is shown in Fig. 3 a pressure reducing valve of the pilot type, in which the main valve is controlled by a pilot valve in a different manner from that involved in the construction of Fig. 2. Referringto Fig. 3, there is shown a tubular body 18 having a high pressure port 1| at one end feeding into a chamber 12, and a low pressure port 13 extending through the side of the body and communicating with a longitudinal bore 14. The upper end of the bore 14 constitutes a poppet valve seat 15, communicating the bore with the chamber 12, and normally closed by a main poppet 15, which is formed integrally with a piston 11, which is sealed with respect to the bore 14 by a sealing ring 18. The piston 'I1 is located below the low pressure port 13. The lower end of the bore 14 is closed by a wall 19. which separates the bore 14 from a larger bore This permits the elimination u 80, which extends into the body 10 from the lower end. A piston 8| is tted in the bore 80 and sealed with respect thereto by a sealing ring 82. A helical loading spring 83 is compressed between the underside of a piston 8| and a screw plug 84, which is threaded into the lower end of the bore and provides for adjustment of the loading of the spring 83.

The piston 8l has a piston rod 85 extending upwardly therefrom through a passage 86 in the wall 19 into the bore 14, and sealed with respect to the passage 86 by a sealing ring 81. This piston rod has an axial passage 88 extending from its upper end and communicating with the bore 80 above the piston 8|.

The main poppet 1E has an axial passage 89 extending therethrough, and the upper end of this passage is adapted to be closed by a pilot poppet 98, having a stem 9| which extends through the passage 89, and is secured to an auxiliary poppet 92 at its lower end. The auxiliary poppet 92 is adapted to close the upper end of the passage 88 in the piston rod 85, Opening movement of the pilot poppet 9|! with respectto the main poppet 1li is limited to a small value by engagement of projections 92| on the upper end of the auxiliary poppet 92 with the lower end of the main poppet 16. The low pressure port 13 iS permanently connected to the upper end of the bore 88 by a fluid passage 93.

The valve of Fig. 3 functions as follows: Assume that the pressure in the low pressure port 13 is Aat a desired predetermined value, and that a source of pressure fluid of higher pressure is connected to the high pressure port 1|. The pressure in the low pressure port 13 is applied through the passage 93 to the upper end of the bore 88, where it is applied to the upper face of the pitson 8| and develops a force thereagainst which is balanced by the loading spring The pilot poppet S0 is seated against the upper end of the passage 89 by the high pressure fluid in the chamber lf2, and the auxiliary poppet 92 is seated against the upper end of the passage 88, so that the lower end of the bore 'M is a closed chamber. l

Now assume that as the result of withdrawal of uid from the low pressure port 13, the pressure in the upper end of the bore 8|) diminishes,`

permitting the loading spring 83 to move the pis ton 8| upwardly. This causes the piston rod 85 to carry the auxiliary poppet 92 upwardly, thereby opening the pilot valve 90, until the projections 92| thereon Contact the piston 11. Prior to opening of the pilot valve 9|), the force of the high pressure fluid in the chamber 12 `acting against the large main poppet 16 held the latter iirmly seated. However, as soon as the pilot valve 98 is cracked, high pressure iiuid from the chamber 12 is admitted through the passage 89 to the lower end of the bore 14, thereby balancing the force of the pressure uid acting against the main poppet 'l5 with an equal force produced by uid at the same pressure acting against the underside of the piston 11. The loading spring 83 is then able to easily lift the main poppet 16, and it moves upwardly to admit pressure fluid from the chamber 12 into the low pressure port 13 in suficient volume to maintain the desired pressure in the port 131 When the pressure in the low pressure port 13 rises above the predetermined range, this pressure acting against the piston 8| moves it downwardly, permitting the pilot poppet 98 to close the upper end of passage 89, after which further downward movement of the piston 8| and its rod 85 carries the .latter iaway from `'the auxiliary poppet 92 ,fxpermittin'g ithe .=.pr.essure ziiuid :to v:be .exhauste'd 'from fthe iundersid'e fo'f. Lthe .piston` e751 through. the passage 88, fthe upper Iend -.of ith@ bore 8.0 :and l.therpassage 1.93, to the ilow :pressure port (1.3. Thereupon, the :highpressure :in the chamberi'lZ Lcloseslthe main Apoppet 16.

The speed with which themainipoppet i6 responds v:to `variations .in .pressure in the xlowtpressure :port 1,3 depends .upon lthe. size :of f the passage 89 vthrough which.1pressure iiuid is admitted Sto the .underside of itheipiston lil, andthe size of the .passage y88 through which pressure 'huid is vente'dfrom lthe'.ulodersidezo'f the piston .'H. `IBy suitably proportioning thepassagesSS andl, any desiredspeedof response of the main poppet 1:6 Lcan b`e obtained.

,'Lh'erate at which Apressure .fluid is admitted fromzzthe chamber l2 .to the underside of the piston "M Jcan lalso'befcontrolled by .limiting the openingmovement ofthe .pilot poppet 90. .It is usuallydesirable :.to provide Jonlyzminute clearancelbetween the projections .02| ofthe auxiliary poppetSZ and fthe `underside of the piston fllto permituthepilot poppet 90 to barely crack.

It willbe observed that duringtheperiod of increase in .pressure ,in the low pressure port 'I3 andith'e upperendof the bore 80, the auxiliary poppet Q2iwill follow thepiston rod'85 very closely, because the slightest cracking of the auxiliary poppet ESZaWayfrOm-the piston rod permits escape of'pressure uid from the lower end of the bore T14 .aand resultant following movement ofthe piston H11-.and main poppet 16.

' Although for the purposeof explaining the invention, :several .different `modifie-ations thereof havebeen des-cribedin detaiLseveral distinctions from theexactconstruction shown will be apparent'to ,thosefskilled in the art and theinventionfis thereforeto be .limited only to the extent set. forth in the appended claims.

fDivisional .application Serial No. `26,432 was ledMay'il, 119,48 claiming the specic construction shown in ]ig.;3.

1. In a pressure reducing valve: a body member :having a longitudinal vpassage therein; a high pressure port communicating rwith one end ofrsaid body passage; a relief port communicating withsaid body-passage at a point longitudinally spaced from said one end; a low pressure portcommun-icating 'with said body passa'ge at a point intermediate said high pressure port .and-said relief port; `a sleeve positioned in said body passage, and means sealing it with saidf'body passage at a Zoneintermediate said high pressure-port and said low pressure port, and at a zone intermediate said low pressure portland said relief port; alateral low pressure port in said sleeve communicating the interior ofthe -s-leeve with said low pressure port in said body'memberya lateral relief port in said sleeve communicating the interiorof the sleeve with said relief port in-saidbody'member; an axial valvev seat in -said `sleeve communicating said high pressure port'with said lateral'low pressurelport; AYla poppet seating against the high pressure fend f ofsaid seat; :a .piston in said sleeve juxtaposedito said .lateral relief ,portlthereim and y having sealing .means .sealing with said 'sleeve at Zones before Vand `beyond Ysaid.=relief port, .and having an :axial passage extending linto said piston .from the :high :pressure end :thereof andy communicating with .said Vlateral relief port; an auxiliary Ipoppet. in axial alignment .with said first mentioned poppet,y and adapted to seat against the endof said axial .piston passage, the said piston and auxiliary poppet sealing said sleeve intermediate said low pressure port and said relief port when .said auxiliary `poppet is seatedagainst-said piston passage; l.spring means urging said-piston towardsaid highpressurefend; and means responsive to :movement "of .said auxiliary poppet by said pistontoW-ardsaid high pressureend Ifor unseating said first .mentioned poppet toadmit fluid from said high pressureport to-saidlow pressure port.

2. A valve asdescribed inA claim -1 .in whichfsaid lastmentioned means comprises: a stem interconnecting `said rst mentioned poppetand said auxiliary poppet.

3. A-valve asdescribed in claim 1 in which said last mentioned means comprises: a partition within said sleeve; a second piston sealing with said sleeve between ysaid partition therein and said lateral low .pressureportg Vmeans connecting said second piston with said first mentioned poppet for `actuating -the latter; a poppet Apassage extending through said second piston and said first-mentioned poppet; a pilot poppet seating against the outer v-end of said poppet passage; `a steminterconnecting said pilot ypoppet'and said auxiliary poppet, Vand extending through Vsaid poppet passage "and through an vaxial passage provided therefor in said partition; said sleeve having a lateral port communicating said low pressure port with the ,interior of said sleeve intermediate said Vpartition and said rst'piston; said `stem havingless clearance with thepassage in said-partition than with said poppet passage, whereby opening-of saidpilot poppet develops a pressure vvbetween said partition and said second piston suflicient to open said .rst mentioned poppet againstztheforce of the pressure fluid in said highpressure port.

SYDNEY E. TESTMAN.

REFERENCES CITED The following references are of record inthe le ofthis patent:

UNITED STATES PATENTS Number Name "Date `650,724 'Metzger May29,j1900 1,180,108 Cash Apr. 18, 1916 1,611,079 Roschanck 'Dec. 14,1926 1,995,826 .Scderberg Mar.26, 1935 2,044,452 `Terry June,16,193,6

FOREIGN PATENTS Number Country Date 1,747 Great'Britain Jan; 26,1893 "724,263 lFrance Jan.-26,1932 

